Uniformly Loaded Simple Beam
For Dimensional Lumber 2-4" thick

When specifying a beam or joist three things are usually considered;
First,is the beam strong enough that it doesn't fail in bending, by the fibers on the bottom being torn apart, a fiber failure.

Second, is the beam stiff enough that there will not be excessive deflection. A bouncy floor, cracked tile or plaster would be examples of this.

Third, is the beam strong enough that its fibers don't slip past one another, bend a magazine and watch the pages slide past one another. This is a horizontal shear failure.


Change these inputs to reflect your variables
The design values for the species and grades in the drop down list are for dimensional lumber 2-4" thick
Load on Beam(pounds) Duration of Load
Span of Beam (inches) Repetitive Member
Width of Beam Size
Depth of Beam Wet Service
Select Species and Grade Incised


Bending Deflection Horizontal shear
Max Moment (ft-lbs) Deflection (inches) Shear (PSI)
Section Modulus Required Max 1/360 (Floor) Section Required
Section Modulus Input Max 1/240 (Roof) Section Input
Section Modulus Pass/Fail Deflection Pass/Fail Shear Pass/Fail

Lumber Design Values

Base Design Values Adjusted for Duration of Load, Repetitive Member Use, Size Factor, Moisture, and Incising
Base Design Values Adjusted Design Values
Allowable Fiberstress in Bending (Fb)(psi) Adjusted Allowable Fiberstress in Bending (Fb')(psi)
Modulus of Elasticity (E or MOE)(million psi) Adjusted Modulus of Elasticity (E or MOE)(million psi)
Allowable Shear (Fv)(psi) Adjusted Allowable Shear (Fv')(psi)
Maximum Compression Perpendicular to Grain (psi) Adjusted Maximum Compression Perpendicular to Grain (psi)
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